Great fun so far, well done! Some general thoughts -

A suicide button would be handy, I've got stuck in the geometry a few times and had to start over instead of restarting from a checkpoint.

Character perks for the skins - extra jump fuel, slower fall time etc. Unique audio rage sound fx for the characters would be really cool and give them some personality. Although alternate characters should be excluded from leaderboards.

Decrease rage sound trigger logic upon death (25% would be ideal for me personally!)

Gallery mode (on the way I know)

Make it easier to determine which levels have been collected of all monies from the map screen, for example by giving the level icon a gold outline.

Enjoying the game so far!